1. Field Of The Invention
This invention generally relates to a mechanism which provides lifting and tilting for heavy containers, and more particularly to an elevatable cradle assembly which is adapted to completely invert gas cylinders such as propane or butane tanks.
2. Discussion Of Relevant Art
Numerous industries employ large containment vessels such as cryogenic fluids, propane, butane and other substances which, in most cases being volatile, are invariably contained within their containments in a liquid form under considerable pressure. Most of the containments have the general shape of cylinders, although in some cases cylindrical tanks, drums or barrels may be substituted with other shapes tending toward more cubical geometries. Irrespective of the containment type, withdrawal of the liquid contents is, in many cases, incomplete. In order to evacuate the remaining liquid contents or otherwise purge the containments, it has been found to be both expedient and economical to invert the containments, preferably by a complete topsy-turvy maneuver, and thereby drain the remaining liquid contents while the inherent volatility of the liquids serves to increase pressure in the containments, thus helping to expel the remaining liquid content.
Having thus explained the need which is presented to the industry, I will now digress into art which has been developed in the past, as well as that which is available in the industry today, for tilting or otherwise inverting tanks, drums, barrels and the like. For most of this disclosure, I prefer to concentrate on containment characterized by modern pressurized, gas-containing cylinders such as are used for propane or butane storage. It should be understood by the reader, however, that such continual reference is by no means meant to limit the invention as to its utility for inverting containments of practically any geometry or size such as would be reasonably encountered in using the mechanism and apparata hereinafter disclosed.
The U.S. Pat. No. 2,670,864 was issued in 1954 for a COMBINED HOIST AND POURING STAND FOR CONTAINERS. The patentee engages a container by envelopment within a cupping framework. Thereafter it is hoisted by lifting the framework between two vertical uprights of a footed stand using a conventional winch. The footed stand, or podium as I choose to term such a mechanism, is asymmetrical, having parallel elongate members extending toward what the patentee terms the front of his apparatus. Once the cupping frame is sufficiently elevated, the container which has been hoisted therein is tilted forward in a portion of the cupping frame that is pivotally mounted to the major elevational frame work. A distinct advantage of this apparatus is that the container or drum being tilted is caused to pivot or rotate about an axis passing through its nominal (when full) center of gravity. Also apparent, however, are two very distinct disadvantages: (1) because the remaining elevational framework and podium structure prevent complete 180.degree. inversion of the containment, the receiving container (if there is one) cannot be placed directly beneath the container being emptied--it must be placed to the fore of the podium; and, (2) because of the inability to rotate 180.degree., along with the constraint offered by the cylindrical type elevational framework, the patented apparatus remains but a pouring stand and will not serve the industry for the specific tank inversion maneuvers which I feel are truly demanded.
Throughout the art there have been myriad disclosures of tilting apparata that range from garbage can tilters to barrel inverters, but provide only a modicum of functionality that I have determined must be developed for the industry. In a more modern vein, there has been effort expended to provide gas tank inversion apparata. The Pro-Chem Company of Middlesex, N.J. catalogues a "Model CE-420 Tank Inverter" which is made to tilt and "invert" LP-GAS cylinders in order to enhance either product evacuation or facilitate repair or maintenance. Utilizing one-person operation, it consists mainly in a base assembly comprising a podium (such as discussed above) having thereon two vertical, rigid supports which pivotally engage a cradle of size sufficient to handle the referenced LP-GAS cylinders (which may range up to 420 lbs). The CE-420 is, however, a ponderous mechanism acquired at considerable investment and which tilts or "inverts" a cylinder in what I feel is a rather bizarre fashion. The cylinder is engaged in the cradle at the front of the podium and, while strapped to the cradle, is inverted, not by a simple pivotation, but by a lifting up and "over-the-shoulder" maneuver which actually moves the cylinder center of gravity in an arcuate motion beginning at the front of the podium and terminating, in the air, proximate the rear of the podium. That such a maneuver exacts a near 180.degree. inversion is not to be contested; however, the heavy duty framework, motive power, harness strengths and inherently unsafe maneuvering of the cylinder certainly demands questioning. What is particularly disconcerting is that several devices of such nature are on the market today; --they move the containment off the firmament and either cantilever it for subsequent rotation fore-aft or they simply, like the CE-420, arcuately motivate it over-the-shoulder in a single topsy-turvy maneuver.